Mullaittivu (Sri Lanka), Jan. 3 (Reuters): Thousands of children whose lives have been upturned by Sri Lanka's worst natural disaster need two things above all, the head of the United Nations Children's Fund said today ' clean water and playtime.

The children of this tiny northeastern fishing village in Tamil Tiger rebel territory were either swept to their deaths by a savage tsunami a week ago, or were scooped out of the water and taken to the safety of refugee camps or relatives' homes inland.

The trauma of losing parents, brothers and sisters will be with them for years. But playing with friends will help them recover, UNICEF executive director Carol Bellamy said on a visit to the rebel-run north.

'The biggest challenge is to make sure the children stay alive ' to avoid the outbreak of disease. One of the biggest problems now is that the still water may be as dangerous as the rushing water that killed in the first place,' she said.

'What children mostly need in a traumatic situation such as this is some normalcy, because this was so abnormal,' Bellamy added. 'Normalcy means being back with family members'being able to play, that's what children like to do. Going to school. That's the best thing.'

Rescue officials say a disproportionate number of children and women were among around 30,000 people killed when giant waves crashed into the Indian Ocean island's southern, eastern and northern shores on December 26. The government says so many children have been orphaned that it has appealed for doctors, psychologists and paediatricians to pitch in and give counselling. 'Counselling will help. But it isn't a matter of counselling as such,' Bellamy said.

Clutching puzzle pieces at a refuge for children in the rebels' northern stronghold of Kilinochchi, 55 km due west, nine-year-old Duwani was one of the lucky ones. Eighty of her schoolmates were swallowed up by the tsunami.

She just wants to play.

'I like games very much,' she said shyly in her native Tamil, as Bellamy inspected a home for mentally disabled children that has been converted into a makeshift refuge for 36 children.

Duwani's school, back in Mullaittivu, like the rest of the village, was decimated.